Telephone system and apparatus therefor.



No. 776,090. PATENTED NOV. 29, 1904.

W. (L RUNGE.

TELEPHONE SYSTEM AND APPARATUS THEREFOR.

APPLICATION FILED DBO. e. 1902.

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PAYTENTED NOV. 29, 1904.

. W. G. RUNGE.

' TELEPHONE SYSTEM AND APPARATUS THEREFOR.

APPLIOATION 21mm 1130. a. 1902. no MODEL.

4 SHEETS-ERR! 2.

PATENTED NOV. 29, 1904.

W. G. RUNGB. TELEPHONE SYSTEM AND APPARATUS THEREFOR.

APPLICATION FILED DBO. 6, 1902.

4 SHEETS-*BKEET 3.

N0 MODEL.

MAI /765s e5 3 No. 776,090. PATENTED'NOV. 29, 1904. W. 0. RUNGE.

TELEPHONE SYSTEM AND APPARATUS THEREFOR.

APPLIGATION FILED DEG. e, 1902.

N0 MODEL.

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I STATES Patented November 29, 1904.

PATENT \WALTER (J. RUNG'E, OF LONDON, ENGLAND.

SPECIFICATION forming part of Letters Patent No. 776,090, dated November 29, 1904.

Application filed December 6, 1902. Serial No. 134,155. (No model.)

Telephone Systems and Apparatus Therelor,

of which the following is a specification.

This invention relates to improvements in telephone systems, the object being to simplify the installation and to provide certain apparatus in a convenient form for this pur pose.

The system is one of the type in which the removal of'the subscribers receiver from its hook momentarily earths one line-wire and actuates an annunciatonsuch as 'an electric lamp, in the exchange. in addition to this usual ann unciator fo r each subscriber an engaged signal is provided in the exchange, such as another electric lamp. This engaged signal is only actuated when both the calling and called subscribers have taken their receivers ofl their hooks, and an arrangement is made whereby the engaged signal is released when either subscriber hangs up his receiver.

The separate parts of the system will now be described with reference to the accompanying drawings, in which Figure l is a diagram of the system. Fig. 2 is a perspective view of aswitch-hook. Fig. 3 is a longitudinal section through the combined jack and relay. Fig. A is an inverted plan of the same, and Fig. 5 is an elevation of an engaged relay and releasing electromagnet with part of the outer shield removed. Fig. 6 is a diagram of a modification of the system.

Referring to Fig. 2, the switch-hook F is connected to one line-wire A. WV hen the receiver is on the hook, the rear end of the hook touches the usual bell-terminal F, so that the subscriber can be rung up. WVhen the receiver is off the hook, the rear end of the hook touches the two talking-circuit contacts F" F in the usual way. Two resilient contact-arms F F are arranged side by side on one side of the hook normally out of contact with the hook or with one another. The arm F, conveniently a flat spring, is connected to a line-wire A. The other arm, F", consists of a wire having its lower end bent in horizontally at right angles toward the hook. On the side of the hook F is a double-beveled projection F, one side of which in metallic connection with the hook, and therefore with the line-wire A, while the other side is of non-conducting material. The arms F F and the projection F are so arranged that when the receiver is on the projection F is below the bent end of the wire F and no contacts are made, and when the receiver is oil the projection F is above the bent end of F and no contacts are made. When the receiver is being taken elf, the hook passes upward and the projection F" (on account of its upper beveled end) passes outside the bent end of the wire F and presses it momentarily against spring F", thus earthing the spring F and line-wire A for a purpose to be hereinafter explained. \Vhen the receiver is being put on, the hook passes downward, and its projection F" (on account of its lower beveled end) passes between the spring F and the bent wire F. The metallic part of the projection thus momentarily comes in contact with the bent wire F, thus earthing the hook and line-wire A fora purpose to be hereinafter explained.

Referring to Figs. 3 and 4, the annunciator comprises a line-relay B, having an armature B, which when attracted by the core is retained by a detent B The detent l5" comprises a pivoted lever having a projection Z) on the end. The armature carries a spring which when the armature is attracted touchesa lamp-terminal B and thus closes the circuit of a lamp B" or other well-known line-signal. Immediately below the annunciator is the metallic plug-socket E, which is connected to one line-wire A. Behind the socket are three springs. The first, E, isconneeted with a line-wire A. The second, l5, forms the terserted the wires E E" are in contact and. the detent B" is 1n its highest position, (if the armature is attracted.) The plug and socket are so arranged that when the plug is inserted the wire E-is pushed out of contact with linerelay terminal E and the wire E comes into contact with terminal D. The socket E is joined to the line-relay terminal E through the outer part of the plug D The inside metallic portion D of the three-way plug makes contact with the spring E lNhen the projection D engages the end b of the detentlever B thelever is tilted so as to release the armature B, as shown in Fig. 3. hen the projection D passes the end 6 the latter falls into a depression D* in the plug, and the lever is then free to act as a detent for the armature B again, although the plug is in the socket.

Referring to Fig. 5, to indicate that both subscribers receivers are off the hooks F a supervisory relay L and signal L are employed, hereinafter called the supervisory signal. One end of this supervisory relay L is connected to an earthed battery O and the other end is arranged in proximity to a contact-breaker L*, the blade of which forms one talking-circuit terminal. l Vhen, therefore, the second-subscribers plug K is in the jack and he removes the receiver from the hook F, one line-wire A is earthed, as above described, and a circuit is completed through the battery O and the supervisory relay L, and the supervisory signal L remains in engaged position so long as both receivers are off, since the supervisory-relay armature L is retained by a detent L after its momentary attraction. The detent L is so connected to the contact-breaker L that its retention causes the blade to leave the supervisory-relay terminal L and come into contact with a second talking-circuit terminal L When clearing out, if one subscriber hangs up his receiver on the hook F the supervisory signal L is put out of action by means of an electromagnet M, which releases the armature detent-lever L, as hereinafter described. The electromagnet-circuit has a gap which is closed by the relay-armature L when in the supervisory position, a second gap at the central terminal D of the three-way plug, and a third gap at 13*, which is closed by the subscribers line-relay B when the receiver is either taken off or put on its hook F. The closing of the third gap 15* puts the electromagnet M in circuit with the battery N and energizes it. The hanging up of one subscribers hook F puts the second linewire A to earth, as explained above, and com pletes a circuit through theline-relay B, thereby actuating the subscribers line-signal B The removal of the plug D from the jack E releases the detent-armature B of the linerelay B and leaves the jack in its normal unconnected position in which no current is being used at all. Preferably both the subscribers line-signals B and the supervisory signal L aresmall incandescent lamps. The earthed wires may obviously be replaced by metallic connections. An important advantage of this invention is that as few relays are employed the number of contacts is considerably less than in former systems. The supervisory signal-relay L and releasing-electromagnet M are conveniently formed on one core and are singlewound. The ends are covered by fiber or the like M, and the coils are separated by a magnetic screen M of iron, to prevent any lines of magnetic force passing from one coil to the portion of core Within the other coil. The two coils are incased in an iron tube M which, with the screen, forms a path for the lines of force outside the coils. One end of the supervisory relay-coil, L, is connected to an earthed battery O. The other end forms one side, L, of a contact-breaker. The blade L of the contact-breaker is in one main wire, K, of the second plug K and the other side, L, of the contact-breaker is in the other main wire, K of the second plug K. The supervisory relay has an armature L, which when attracted is retained by a detentlever L and when this occurs the armature falls into a recess L in the detent and allows the blade L of the contact-breaker to come into contact with the main-wire terminal L thus closing the talking-circuit. The armature L at the same time closes the circuit of the engaged supervisory signal L and lights a lamp or the like and also closes one gap in the circuit of the electromagnet M. The second plug K is provided with an electromagnetterminal K in the same way as the first, and therefore if either receiver is hung up on the hook F the corresponding line-relay B closes the electromagnet-circuits B and its armature M* is attracted. This motion actuates a rod M, which releases the detent L of the armature L of the supervisory relay L through a .bell-crank lever or similar device.

Referring to Fig. l, the connections of the system are as follows: One line-wire, A, extends from terminal F and subscribers instrument tojack-terminal E. Another line-wire, A, extends from the hook F to the socket One plug-wire, D, extendsfrom the plug to the upper hand-lever terminal H Another plug-wire, D extends from the plug to the lower hand-lever terminal H. The hand-lever when pressed over to the left side puts these two plug-wires into connection with the operators instrument. WVhen the hand-lever is pressed to the right, the called subscriber is put into connection with the magneto J. A third plug-wire D K extends from each plug to the releasing-electromagnet M. One main earthed battery, O, is in connection with the line-relays B and also with the supervisory relay L. A second battery N is connected with one terminal of the engaged lamp L and with a terminal on the armature L, so that when the armature L is attracted the supervisory lamp L is lighted. The battery N is also connected with the releasingelectromagnet IIO Waoeo M. In addition to being connected to a contactat the hand-lever ii the magneto .l is joined to a spring-contact J, operating in conjunction With the armature L of the supervisory relay, so that the magneto is cut out when the supervisory lamp is lighted and the subscribers are talking.

, The operation of the system as follows: When the first subscriber takes the receiver oil the hook F, his bell-circuit is broken at ll" and the talking-circuit made at F F. On passing upward the projection F on the hook presses the earthed spring F against the lirst line-wire terminal F and completes the circuit of the line-relay B, which operates the line-signal B The circuit is then as follows: from the earthed battery C, through line-relay B and springs E and E and line-Wire A, through spring F and earthed terminal F This circuit is only momentary; but as the linerelay armature B is caught by the detent B the lamp-circuit remains closed and the lamp B lighted. The circuit of the lamp is from the battery N to the armature B, to contact B, and thence by a wire to the lamp B and back to the battery N. The operator then inserts the first plug D in the first-subscribci"s jack E and joins the line-wires D to E and D to E throws the line-relay out of contact with the first line-wi re A by separating spring E from E and into contact with the second line-wire A by contact of l) and E, and coinpletes part of the electromagnet circuit through the inner portion l) of the plug. At this stage the talking circuit is from F, through hook F and line-wire A, to socket l thence through plug 1) to the second terminal H of the operators hand-lever H, also from Fathrough the line-wire A and jack-spring E, into plug-wire D and thence to the lirst terminal H of the operators hand-lever. The hand-lever is then pressed into contact with the terminals of the operators instrument in the usual way. The operator being now in talking connection with the lirst subscriber obtains the required number and inserts the second plug K in the socket of that number and then moves the hand-lever H, so as to cut .out the operators telephone and to put the magneto J in connection with the wires of the second plug K in the usual Way to ring up the second subscriber. The circuit is from the magneto J, through the spring J, to the lirst hand-lever terminal H, through plug-Wire K and line-wire A to the called subscribers bell, and back through the line-Wire A, socket it, plug K to the second hand'lever terminal 11 and back to the magneto J. The hand-lever H springs back or is moved back so as to put the second plug-wires into contact with the talking-circuit. The talkin g-circi'ii t is now from the calling -subscribers instrument, through the two line-wires, to the terminals H H" of the hand-lever, as above described. One branch of the talking-circuit is complete I the supervisory signal-relay L.

"from the second hand lever terminal H through plug K and socket E to the called instrument. The other branch ol the talkingcircuit passes from the lirst hand-lever terminal ii to the contact L, where there is a gap. From the other side oi the ga1' -namel y, the blade L-the circuit is completed through the plug-wire ii to the called instrument. it only there'lore remains to close the gap L L to complete the talking'cireuit. The second subscriber then removes his receiver from the hook F, and in doing so puts to earth his first linewire A, as above described, and energizes The plug K being in its socket, the energizing oi the supervisory relay is through the following circuit: from the earthed battery (J, through the coil L and terminal L, to the blade L and. thence through the plug-wire K and linewire A to the spring, which is momentarily earthed as the called subscribei"s hook i rises. The supervisory relay L being earthed attracts its armature L and actuates the supervisory signal L, the lighting'circuit being from battery N, through lamp L and contact on the armature L, back to the battery N. The armature L then engages the reccssL in the detent L and allows the contactbreaker blade L" to complete the talkingcircuit by leaving L and coming into contact with L. The supervisory signal L is thus in operation while the subscribers are talking. The talking-circuit is as follows: from the callingsubscribefis instrument, through line-wire A, spring l l, plug-terminal D, to hand-lever terminal H, to contact L", blade L", and through the plug-wire. K and line-wire A to the called subscribers instrument and back through line-wire A and plug-wire K to the second hand-lever terminal H, through plug-wire .i), socket E, and line-wire A to the calling-subscribefls instrument. When one or other ol the subscribers hangs up his receiver on the hook .F, the projection F on the hook makes contact with the earthed wire F and therefore completes the line-relay circuit B through the second linewire A, the circuit being from battery U, through line-relay B, spring E plug l)", and socket l line wire A, hook F, and projection F, to the earthed wire F The line-signal B is then operated and the electromagnet-circuit is completed at B", so that the su pervisory signal L is put out oi? operation, as above described. The circuit of the releasing-electromagnet from the battery N,

through the armature L and through an ar' mature-contact, to coil M, thence to the plugterminals l) and K, through the spring-contact It, contact B", and line-relay armature B, back to the battery 1". The operator on seeing that the subscribers lamp l)" is lighted removes the plug 1) from the socket 1E and by sodoing replaces all the contacts in their original positions, as the armature B is 1ne chanically released from its detent B and the spring E again comes into contact with the spring E hen it is necessary to make a connection between two operators, the apparatus of the second operator acts in the same way as that of a called subscriber.

Referring to Fig. 6, instead of using a mechanical detent B and actuating the line-relay B by a momentary current the detent may be dispensed with. In this case the hook F is provided with an extension F, which in moving up or down is arranged to come into contact with a projection O on the armature O of a relay 0. One end, 0 of the relay-winding is earthed, and the other end, 0*, terminates in a contact-piece in proximity with a spring P, connected with an insulated metallic piece P on the hook extension F. The metallic piece is arranged to come into contact with a terminal Q, of the line-wire A when the extension F moves downward and also to come into contact with. a terminal Q, of the other line-wire, A, when the extension moves upward. The terminal 0* and spring P are pressed together when the relay 0 attracts its armature O, which is, however, insulated from these. The hook F is also provided with a contact-piece E, which touches the armature when it is not attracted, the armature being permanently connected with the second line-wire A. In this arrangement when the first subscriber removes his receiver from the hook F the extension F, moving downward, pushes the armature 0 up to the relay 0. Contact is thus made between the spring P and the terminal 0*. At the same time the metallic piece P comes into contact with the terminal Q, and therefore through the line-wire A, springs E E and relay B to the earthed battery C. The relays B and O are energized and the armatures are held up. Then, however, the plug D is inserted in the jack E, the spring E leaves the spring E and the relay-circuits are broken, with the result that the signal-lamp R is extinguished and the armature O falls back, breaking the connection 0* P and making the connection E 0, thereby closing the talkingcircuit. The armature 0 may be provided with a signal-disk O, the movements of which indicate to the subscriber the state of his circuit. In this case two supervisory signal-relays R S are used, the talking-circuit wires of the two plugs being provided with condensers V, which separate the engaged signal relays. The windings of one supervisory relay R are connected with a talking-circuit wire D of one plug D, and the windings of the other supervisory relay S are connected with one talking-circuit wire K of the an-' sweringplug K. The supervisory relays are provided, as before, with armatures R S, having detents R S with beveled edges R* S", which cause the detents to move downward when the armatures R S are attracted,

thus raising the blades R S of the contactbreakers. Before the armatures are attracted the blades R S are in contact with terminals R S in connectionwith an earthed battery 0. The windings of the releasingelectromagnets T U, as before, are connected with the tips D K of the plugs and with the springs on the armatures R S, battery connections J J being arranged to come into contact with the springs when. thearmatures R are attracted. WVhen the operator inserts the plug D in the calling-subscribers jack, the winding of the supervisory relay R is connected through the talking-circuit wire D, the line-wire A, and the contact 0* P to earth and the supervisory signal-lamp R is actuated, the armature R is held up, and the circuit is broken at R. The operator obtains the required number in the usual way and inserts the second plug K in the jack of the answering subscriber. When the answering subscriber takes his receiver of]? the hook F, the corresponding armature O is pushed against the relay and the contacts 0 P and Q P are made and the line-wire A is earthed. The supervisory signal-relay S then attracts its armature and the lamp S is lighted. lVhen either subscriber hangs up his receiver, the line-wire A is earthed through the contacts 0* P and P Q, and the releasing-electromagnet is energized, thereby extinguishing the corresponding supervisory signal-lamp R say. Owing to the fact that the supervisory signals are separate from one another the remaining supervisory signal S still remains in operation,

' so that the operator does not remove the plugs until both supervisory signals R S hax e been extinguished and both the line-signals B have been lighted.

What I claim as my invention, and desire to secure by Letters Patent, is

1. A subscriber and exchange telephone system comprising two line-circuit wires between the subscribers station and the exchange, two plug-circuit wires in the exchange connectible respectively with the two line-circuit wires, a supervisory signal-relay at the exchange in circuit with the first circuit-wire and with an earthed battery, means for earthing the first circuit-wire at the subscribers station, means for retaining the supervisory signal in operation when actuated, and an electroinagnet for releasing the supervisory signal in circuit with the second circuit-wire and a battery.

2. A subscriber and exchange telephone system comprising two line-circuit wires between the subscribers station and the exchange, two plug-circuit wires in the exchange, connectible respectively with the two line-circuit wires, a supervisory signal-relay at the exchange in circuit with the first circuit-wire and with an earthed battery, means for earthing the first circuit-wire at the subscribers station, means for retaining the supervisory signal in operation when actuated, an electromagnet for re- IIO leasing the supervisory signal in circuit with the second circuit-wire and a battery, one gap in the circuit and means controlled by the subscriber for closing the gap.

3. A subscriber and exchange telephone system comprising two line-circuit wires between a subscriber and the exchange, a subscribefis signal-relay at the exchange in circuit with the first line-wire and an earthed battery, two plug-circuit wires in the exchange connectible respectively with the two line-circuit wires, a supervisory signal-relay at the exchange in circuit with the first circuit-wire and with an earthed battery, means for earthing the first circuit-wire at a subscribers station, means for retaining the supervisory signal in operation when actuated, an electromagnet for releasing the supervisory signal in circuit with the second circuit-wire and a battery, a gap in the circuit and means controlled by the subscriber for closing the gap.

4. A subscriber and exchange telephone system comprising two line-circuit wires between a subscriber and the exchange, a subscribers signal-relay at the exchange in circuit with the first line-wire and an earthed battery, two plug-circuit wires in the exchange connectible respectively with the two line-circuit wires, means controlled by the plug for putting the subscribers relay out of circuit with the lirst line-wire into circuit with the second, a supervisory signal-relay at the exchange in circuit with the first circuit-wire and with an earthed battery, means for earthing the first circuitwire at a subscribers station, means for retaining the supervisory signal in operation when actuated, an electromagnet for releasing the supervisory signal in circuit with the second circuit-wire and a battery, a gap in the circuit and means controlled by the subscriber for closing the gap.

5. A subscriber and exchange telephone system comprising-two line-circuit wires between a subscriber and the exchange, a subscribers signal-relay at the exchange in circuit with the first line-wire and an earthed battery, two plug-circuit wires in the exchange connectible respectively with the two line-circuit wires, means controlled by the plug for putting the subscribers relay out of circuit with the first line-wire int-o circuit with the second, a supervisory signal-relay at the exchange in circuit with the first circuit-wire and with an earthed battery, means "for earthing the first circuit-wire at a subscribcrs station, means "for retaining the supervisory signal in operation when actuated, an electromagnet for releasing the supervisory signal in circuit with the second circuit-wire and a battery, a gap in the circuit, means controlled by the subscriber for closing the gap, means at the subscribers station for earthingthe first line-wire and means for earthing the second line-wire.

6. A subscriber and exchange telephone system comprising two hne-circu1t wires between a subscriber and the exchange, a subscribefs signal-relay at the exchange in circuit with the first line-wire and an earthed battery, two plug-circuitwires in the exchange connectible respectively with the two linecircuit wires, means controlled by the plug for putting the subscribefis relay out of circuit with the first line-wire into circuit with the second, a supervisory signal-relay at the exchange in circuit with the first circuit-wire and with an earthed battery, means for earthing the first circuit-wire at a subscribers station, means for retaining the supervisory signal in operation when actuated, an electromagnet for re leasing the supervisory signal in circuit with the second circuit-wire and a battery, a gap in the circuit, means controlled by the subscriber for closing the gap, means at the subscribers station for earthingthe first line-wire when the receiver is removed from the hook and means for earthing the second line-wire when the receiver is replaced.

7. A subscriber and exchange telephone system comprising two line-circuit wires between a subscriber and the exchange, a subscribers signal-relay at the exchange in circuit with the first line-wire and an earthed battery, two plug-circuit wires in the exchange connect ible respectively with the two line circuit wires, means controlled by the plug for putting the subscribers relay out of circuit with one line-wire into circuit with the second, a supervisory sigi'ial-relay at the exchange in circuit with the first circuit-wire and with an earthed battery, means for earthing the first circuit-wire at a subscribers station, means for retaining the supervisory signalin operation when actuated, an electromagnet for releasing the supervisory signal in circuit with the second circuit-wire and a battery, one gap in the circuit and means controlled by the plug for closing the gap, a second gap in the circuit and means controlled by the armature oi the engaged relay for closing it, means at the subscribers station for earthing the first linewire when the receiver is removed. from the hook and means for earthing the second line wire when the receiver is replaced.

8. A. subscriber and exchange telephone system comprising-two line-circuit wires between a subscriber and the exchange, a subscribers signahrelay at the exchange in circuit with the first line-wire and an earthed battery, two philg-circuit wires in the exchange connectible respectively with the two line '7 circuit wires, means controlled by the plug for putting the subscribcfis relay out of circuit with one line-wire into circuit with the second, a si'lpervisory signal-relay at the exchange in circuit with the first circuit-wire and. with an earthed battery, means for earthing the first circuit-wire at a subscribers station, means :t'orretaining the supcn'visory signal in operation when actuated, an electromagnet for releasing the supervisory signal in circuit with the second circuit-wire and abattery, one gap in the circuit and means controlled by the plug for closing the gap, a second gap in the circuit and means controlled by the armature of the engaged relay for closing it, a third gap in the circuit and means controlled by the armature of the subscribers relay for closing it, means at-the subscribers station for earthing the first line-wire when the receiver is removed from the hook and means for earthing the second line-wire when the receiver is replaced.

9. A subscriber and exchange telephone system comprisingtwo line-circuit wires between a subscriber and the exchange, a subscribers signal-relay at the exchange in circuit with the firstline-wire and an earthed battery, two plug-circuit wires in the exchange connectible respectively with the two line circuit wires, means controlled by the plug for putting the subscribers relay out of circuit with the first line-wire into circuit with the second, a supervisory signal-relay at the exchange in circuit with the first circuit-wire and with an earthed battery, means for earthing the first circuit-wire at a subscribers station, means for retaining the supervisory signal in operation when actuated, an electromagnet for releasing the supervisory signal in circuit with the second circuit-wire and a battery, a gap in the circuit, means controlled by the subscriber for closing the gap, means at the subscribers station for earthing the first linewire and actuating the subscribers signal-relay when the receiver is removed from the hook, means for releasing the subscribers relay when the plug is inserted in the jack, means for earthing the second line-wire and actuating the subscribers signal-relay when the receiver is replaced and means for releasing the subscribers relay when the plug is removed from the jack.

10. A subscriber and exchange telephone system comprising two line-circuit wires between a subscribers telephone and an exchange-jack, two plug-circuit wires in the exchange which can be connected respectively with the two line-circuit wires by inserting a plug in the jack, a supervisory signal-relay at the exchange in circuit with the first circuitwire and with an earthed battery and means at the subscribers telephone for earthing the first circuit-wire and actuating the supervisory signal-relay, an armature-detent for retaining the supervisory signal in operation when actuated and an electromagnet for releasing the armature in circuit with the second circuitwire and a battery.

U 11. A subscriber and exchange telephone system comprising two line-circuit wires between a subscribers telephone and an exchange-jack, two plug circuit-wires in the exchange which can be connected respectively with the two line-circuit wires by inserting a plug in the jack, a supervisory signal-relay at the exchange in circuit with the first circuitwire and with an earthed battery, means at the subscribers telephone for earthing the first circuit-wire and actuating the supervisory signal-relay, an armature-detent for retaining the supervisory signal in operation when actuated, an electromagnet for releasing the armaturein circuit with the second circuit-wire and a battery, a gap in the circuit and means controlled by the subscriber for closing the gap.

12. A subscriber and exchange telephone system comprising two line-circuit wires between a subscribers telephone and an exchange-jack, a subscribers signal-relay at the exchange in circuit with the first line-wire and an earthed battery, two plugcircuit wires in the exchange which can be connected respectively with the two line-circuit wires by inserting the plug in the jack, a supervisory signal-relay at the exchange in circuit with the first circuit-wire and with an earthed bat tery, means at a subscribers telephone for earthing the first circuit-wire and actuating the supervisory signal-relay, an armature-detent for retaining the supervisory signal in operation when actuated, an electromagnet for releasing the armature in circuit-with the second circuit-wire and with a battery, a gap in the circuit and means controlled by the armature ot' the subscribers relay for closing the gap.

13. A subscriber and exchange telephone system comprising two line-circuit wires between a subscribers telephone and an exchange-jack, a subscribers signal-relay at the exchange in circuit with the first line-wire and an earthed battery, two plug-circuit wires in the exchange which can be connected respectively with the two line-circuit wires by inserting the plug in the jack, means controlled by the plug for putting the subscribers relay out of circuit with one line-wire into circuit with the second, a supervisory signal-relay at the exchange in circuit with the first circuitwire and with an arthed battery, means at a subscribers telephone for earthing the first circuit-wire and actuating the supervisory signal-relay, an armature-detent for retaining the supervisory signal in operation when actuated, an electromagnet for releasing the armature in circuit with the second circuit-Wire and with a battery, a gap in the circuit and means controlled by the armature of the subscribers relay for closing the gap.

14. A subscriber and exchange telephone system comprising two line-circuit wires between a subscribers telephone and an exchange-jack, a subscribers signal-relay at the exchange in circuit with the first line-wire and an earthed battery, two plug-circuit wires in the exchange which can be connected respectively with the two line-circuit wires by inserting the plug in the jack, means controlled by the plug for putting the su bscribers relay out of circuit with one line-wire into IIO circuit with the second, a supervisory signal-relay at the exchange in circuit with the first circuit-wire and with an earthed battery, means at a subscribefis telephone for earthing the first circuit-wire and actuating the supervisory signal-relay, an armature-detent for retaining the'siuiiervisory signal in operation when actuated, an electromagnet for releasing the armature in circuit with the second circuit-wire and with a battery, a gap in the circuit, means controlled by the armature of the subscribers relay for closing the gap, means controlled by the subscribefls hook for earthing the first line-wire and means controlled by the subscribers hook for earth ing the second line-wire.

15. A. subscriber and exchange telephone system comprising two line-circuit wires between a subscribers telephone and an ex change-jack, a subscribers signal-relay at the exchange in circuit with the first line-wire and an earthed battery, two plug-circuit wires in the exchange which can be connected respectively with the two line-circuit wires by inserting the plug in the jack, means controlled by the plug for putting the subscribers relay out of circuit with one line-wire into circuit with the second, a supervisory signalrelay at the exchange in circuit with the first circuit-wire and with an earthed battery, means at a subscribers telephone for earthing the first circuit-wire and actuating the supervisory signal-relay, an armature-detent for retaining the supervisory signal in operation when actuated, an electromagnet for releasing the armature in circuit with the second circuit-wire and with a battery, a gap in the circuit, means controlled. by the armature of the subscribers relay for closing the gap, means controlled by the subscribers hook for earthing the first line-wire when the receiver is removed from the hook and means controlled by the subscribers hook for earthing the second line-wire when the receiver is replaced.

16. A subscriber and exchange telephone system comprising two line-circuit wires between a subscribers telephone and an exchange-japk, asubscribe1"s signal-relay at the exchange in circuit with the first line-wire and an earthed battery, two plug-circuit wires in the exchange which can be connected respectively with the two line-circuit wires by inserting the plug in the jack, means controlled by the plug for putting the subscribers relay out of circuit with one line-wire into circuit with the second, a supervisory signal-relay at the exchange in circuit with the first circuitwire and with an earthed battery, means at a subscribers telephone for ear-thing the first circuit-wire and actuating the supervisory signal-relay, an armature-detent for retaining the supervisory signal in operation when actuated, an electromagnet for releasing the armature in circuitwith the second circuit-wire and with a battery, a gap in the circuit, means controlled by the armature ol' the subscribers relay for closing the gap, means controlled by the subscribers hook for earthing the first line-wire and actuating the su bscribers signalrelay, means for releasing the subscribe1"s signal when the plug inserted in the jack, means controlled by the hook for ear thing the second line-wire and actuating the subscribers signalrelay when the receiver is replaced and means for releasing the subscribefis signal when the plug is removed from the jack.

17. A. subscriber and exchange telephone system comprising two line-circuit wires between a subscribefis telephone and an exchange-jacl a subscribefis signal-relay at the exchange in circuit with the first line-wire and an earthed battery, two plug-circuit wires in the exchange which can be connected respectively with the two line-circuit wires by inserting the plug in the jack, a supervisory signal-relay at the exchange in circuit with the first circuit-wire and with an earthed battery, means at a subscribers telephone for earthing the first circuit-wire and actuating the supervisory signal-relay, an armature-detent for retaining the supervisory signal in operation when actuated, an electromagnet for releasing the armature in circuit with the second circuitwire and with a battery, a gap in the circuit, means controlled by the arl'nature ot' the subscribers relay for closing the gap, a second gap in the circuit and means controlled by the plug for closing the gap.

18. A subscriber and exchange telephone system comprising two line-circuit wires between a subscribers telephone and an exchange-jack, a subscribers signal-relay at the exchange in circuit with the first line-wire and an earthed battery, two plug-circuit wires in the exchange which can be connected respectively with the two line-circuit wires by insertin the plug in the jack, a supervisory signal-r'elay at the exchange in circuit with the first circuit-wire and with an earthed battery, means at a subscribefls telephone for earthing the first circuit-wire and actuating the supervisory signal-relay, an armature-detent for retaining the supervisory signal in operation when actuated, an electromagnet for releasing the armature in circuit with the second circuitwire and with a battery, a gap in the circuit, means controlled by the armature oi the subscribers relay for closing the gap, a second gap in the circuit, means controlled by the plug for closing the ga t), a third gap in the circuit and means controlled by the armature of the engaged relay for closing it.

in testimony whereof .l have signed my name 

